The subject matter of the invention is a clamping lever with a vertically adjustable thrust bearing, whose cross hole does not wear out in the region of the tension lever and that the tension lever always exhibits a maximum clamping power.
A clamping lever is used for various clamping tasks. One typical example is the construction of such a clamping lever as an eccentric tension lever; however the invention is not restricted to this example.
Such eccentric tension levers are used for clamping tasks in machine building; however they are also used for example for the securing of the hubs of bicycle wheels at the front wheel forks or rear stays of a bicycle.
When an eccentric tension lever is mentioned in the following invention description, attention is drawn again to the fact that the invention is not restricted to this. Instead of an eccentric clamping surface so-called spiral-shaped clamping surfaces can also be used.
In the case of the named clamping levers according to the state of the art the clamping lever should be brought from its most upright possible, slack position into a folded, taut position. The release position is namely characterized in particular in that the hand-operated lever is located in an upright pivotal position, while the taut position preferably should be characterized in such a way that the clamping lever is in a somewhat horizontal taut position. By means of these two end positions (release position and taut position) the best results are attained ergonomically.
However, the fact that it is not always possible for specified clamping tasks to bring the clamping lever in its taut position into its most favorable position (preferably horizontal position) is a disadvantage of the known clamping lever.
Thus when clamping position is mentioned, by that it is meant that the clamping lever is brought into its most favorable mechanical engineering pivotal movement, i.e. the clamping lever in the taut position should not be in the way, it should have the most favorable position ergonomically and in the embodiment as an eccentric, should achieve the greatest gripping power.
Up to now people have solved this problem by arranging a tapped hole in the region of the cross bolt which serves as a drag bearing for the clamping lever, wherein a clamp bolt engages in the cross bolt, said clamp bolt being constructed vertically adjustable with its threading in the region of the cross bolt.
Therewith the possibility existed that for securing of a specified taut position the clamping lever could first be twisted, in order in this way to bring the clamp bolt into a favorable taut position and then move the clamping lever in order to tighten it.
However, in the process it must be taken as part of the bargain that the taut position of the tension lever can be unfavorable for operation.
In another embodiment it is known to construct the tension bolt itself, which is used for tensioning between the surfaces to be tensioned and penetrates these surfaces, to be vertically adjustable.
By means of twisting this tension bolt constructed as a threaded bolt the taut position can hence be set also before moving the tension lever.
A third known embodiment provides a tension bolt for setting the tension height, said tension bolt penetrating both plates or elements to be tensioned with a through borehole and bearing a threading on its free lower end onto which a nut is screwed. Consequently by means of the adjustment of this nut the tension height can also be set.
The named embodiments suffer from the drawback that the tension height can only be adjusted if one gets hold of the underside of the threaded bolt and the threaded nut located there.
In the case of the other described embodiment, in which the threaded bolt penetrates the cross bolt of the tension lever and a vertical adjustment of the tension bearing is possible there, the disadvantage exists that a sensitive setting of the elevation of the tension bearing is not possible. This setting depends on the thread pitch of the tension bolt penetrating the cross bolt, which is associated with disadvantages. By means of appropriate twisting in the region of the thread pitch therefore an unfavorable, undesirable tension position can again be achieved.
In other respects due to the tapped hole penetrating the cross bolt the cross section of the cross bolt is weakened and as a result the entire clamping transfer is no longer secure.
In addition the aforementioned embodiments of a tensioning device exhibit the disadvantage that due to the pivoting of the pivoted lever with a bearing bolt the bore of the bearing in the pivoted lever wears itself out due to the swivel motion of the pivoted lever that has been executed multiple times, since the bearing bolt in the bore of the bearing executes a frictional effect.